So-called peak detectors have been used to monitor an applied signal power in a circuit. A primary output of the peak detector is a voltage having a magnitude that is related to the power level. However, at low power levels the magnitude of the output voltage is small and, as a result, the output of the peak detector is strongly influenced by any drift in bias potentials, supply voltage, and the detecting device itself (e.g., a diode). The temperature dependance of the detector device alone has been found to have a significant impact on the accuracy of the output voltage.
The problem due to temperature drift has been addressed in the prior art by using an additional temperature dependent device to compensate for the drift of the detector device. The accuracy of the compensation thus relies on a uniformity of the temperature characteristics of the detector device and the compensating device, as well as on a close physical spacing of these two devices in order to avoid any deviation in temperature between the devices.
It has also been observed that the aging of the components may degrade the compensation, and some prior art circuits have thus required testing and tuning.
Reference can be had to U.S. Pat. Nos 4,523,155, 4,970,456, 5,222,104 and 5,287,555 for teaching various conventional power control circuit arrangements and detectors.